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Full text of "The manufacture and properties of iron and steel"

INFLUENCE OP HOT WOEKING ON STEEL.
261
little importance as long as the reduction is sufficient, for in this matter the old adage is strictly applicable: "Enough is as good as a feast." This will be shown by Tables XIV-C and XIV-D, which investigate the effect of work on billets made from ingots 16 inches square and which thus had an all-sufficient reduction to begin with.
TABLE XIV-C.
Influence of Thickness of Test-Piece on the Physical Properties when the Percentage of-Reduction in Rolling is Constant for all Thicknesses; the Finished Bars in each Case having a Sectional Area of about 8 Per Cent, of the Billet.
	a •H	i inches.	Ultimate strength; Ibs. per sq. inch.		Elastic limit; pounds per square inch.		Elongation ir 8 inches ; per cent.		S"	
8	•13	fl	(				1		|	
1	s	IT	•8^	H '	^n;	•8	•as*	3	^^;	•a <3
§ •8 «	iQ to <H« I!	^ •3 y> 8	inished usual te peratur<	•e-g fl2^ •a 3 d .S'G^	Inished usual te peratur*	inished dull red heat.	•dSg .ssl .20 2 2 to o> .a da	inished dull red heat.	inished usual te peratur<	inished dull red heat.
N	CQ	QQ	ft	ft	ft	ft	ft	ft	ft	ft
	4x4	2x%	51640	51280	83440	85380	87.50	29.50	60.1	60.9
	8%x85Mj	2xVj	51120	62840	82650	85410	82.50	88.75	66.4	55.6
4606	8x3	2x%	50850	61970	85700	87860	82.50	80.00	60.8	68.9
	2J^x2%!	2xVi	53820	58200	87860	41400	81.25	81.50	61.0	66.2
	2xl/jj	2x^		68860		50620		19.75		68.4
	g4x4	2x%	59540	60160 '	87050	89840	85.00	81.00	60.0	57.4
		2x%(	59780	60490	88100	40490	29.75	82.60	66.4	55.1
8227	8x8	2x%	60950	61890	42110	42090	80.00	80.50	60.0	55.9
	2^x25^		62350	62700	43070	46680	27.50	28.75	60.7	63.3
	2x1%	2xf|	65130	67470	52180	57880	26.25	23.75	68.9	67.5
	4x4	2x%	67860	68140	42850	44050	25.00	24.25	40,8	43.9
1609	8%x8%	2x%	67550	68040	43190	45560	26.25	28.25	46.1	46.6
	8x3	2x%	67470	68300	44090	46610	26.25	23.25	68.2	50.3
	4x4	2x%	72840	78260	47080	49160	25.00	24.00	40,7	40.8
	35^x85^	2x%	71230	78510	46010	50830	26.25	25.00	40.5	43.5
1440	8x3	2x%	72950	78710	48760	50540	26.25	22.00	62.1	43.1
	2J^x2J^	2x^1	73620	75650	51550	58280	26.25	26.75	45»9	52.1
	2x1%	2x%	78560	79260	68140	63820	22.75	25.25	52.0	50.4
It will be found from a detailed comparison of these tables that there is little difference between the bars of the same thickness, even though rolled from different-sized billets. There is a gain in ultimate strength as the thickness decreases, this being most marked in the cold-finished bars, but the differences are not very marked except in the case of the one-eighth-inch. The elastic limit follows the same- law, but it is raised more than the ultimate as the bar gets thinner. The elongation varies irregularly, but, as a rule, it remains unaffected except in the one-eighth-inch,, where it is low-